Abstract
Combined multi-wavelength aerosol Raman lidar and sun photometry measurements were performed during the HYGRA-CD campaign over Athens, Greece during May-June 2014. The retrieved aerosol optical properties (3 aerosol backscatter at 355-532-1064 nm and 2 aerosol extinction profiles at 355-532 nm) were used as input to an inversion code to retrieve the aerosol microphysical properties (effective radius reff and number concentration N ) using regularization techniques. Additionally, the volume concentration profile was derived for fine particles using the LIRIC code. In this paper we selected a complex case study of long-range transport of mixed aerosols (biomass burning particles mixed with dust) arriving over Athens between 10-12 June 2014 in the 1.5-4 km height. Between 2-3 km height we measured mean lidar ratios (LR) ranging from 45 to 58 sr (at 355 and 532 nm), while the Angstrom exponent (AE) aerosol extinction-related values (355nm/532nm) ranged between 0.8-1.3. The retrieved values of reff and N ranged from 0.19±0.07 to 0.22±0.07 μm and 460±230 to 2200±2800 cm-3 , respectively. The aerosol linear depolarization ratio (δ) at 532 nm was lower than 5-7% (except for the Saharan dust cases, where δ~10-15%).
Highlights
The HygrA-CD campaign was an international field campaign which took place in Athens, Greece between 15 May to 22 June, 2014, in the frame of the Initial Training on Atmospheric Remote Sensing (ITARS) project
Despite recent progress documented in the latest Intergovernmental Panel for Climate Change (IPCC), the uncertainty about the current level of radiative forcing due to aerosols (0.5 Wm-2) is still relatively large compared to that of global warming gases (0.25 Wm-2)
In order to clarify the mechanisms of aerosol radiative forcing and reduce the respective uncertainties, detailed knowledge of the vertical profiles of the particle optical, microphysical (reff, surface-area concentration, N, single-scattering albedo (ω) and mean complex refractive index) and chemical properties, as well as their mass concentrations are required [1,2]
Summary
The HygrA-CD campaign was an international field campaign which took place in Athens, Greece between 15 May to 22 June, 2014, in the frame of the Initial Training on Atmospheric Remote Sensing (ITARS) project. HYGRA-CD (http://hygracd.impworks.gr) brought together a suite of different instruments and expertise aiming to enhance our understanding on the impact of aerosols and clouds on weather and climate. It was based on the synergy between remote sensing and in-situ instrumentation, making use of numerical weather prediction and atmospheric modeling. It is well established that tropospheric aerosols play a crucial role in climate change through scattering (cooling effect) and absorbing (warming effect) incoming solar and outgoing thermal radiation [1]. Despite recent progress documented in the latest Intergovernmental Panel for Climate Change (IPCC), the uncertainty about the current level of radiative forcing due to aerosols (0.5 Wm-2) is still relatively large compared to that of global warming gases (0.25 Wm-2). In order to clarify the mechanisms of aerosol radiative forcing and reduce the respective uncertainties, detailed knowledge of the vertical profiles of the particle optical (backscatter and extinction coefficients, AE and LR), microphysical (reff, surface-area concentration, N, single-scattering albedo (ω) and mean complex refractive index) and chemical properties (water content, dry chemical composition), as well as their mass concentrations are required [1,2]
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